let a = true;
let b = String(a);
console.log(typeof b)


a = '3';
b = '1';
//除法直接转
console.log(b / a)
console.log(typeof b)
b = Number(b);
console.log(typeof b)
console.log(Number(null))
console.log(Number(undefined))
console.log(Number(true))
console.log(Number(false))
console.log(Number('  123  '))

console.log(Boolean(1))
console.log(Boolean(0))
console.log(Boolean("0"))
console.log(Boolean("hello"))
console.log(Boolean(""))
console.log(Boolean(" "))
